In an overflowing lecture hall, the prophet is preaching to a group of students. He has a droopy mustache and red-rimmed eyes and he lurches around the room, interspersing his gospel with giggly asides. His audience of University of Texas computer scientists sits quietly and rapt, some rocking in their chairs the way Bill Gates does.

"Okay, so here's how we're going to take over the world," the prophet says.

His name is Eric Raymond, and he is leading a grass-roots crusade that few Americans have heard of, a crusade that is building at the hardest core of the technology world -- in computer labs, Internet chat rooms and hacker conventions.

Here, not in a Washington courthouse or Silicon Valley cubicle, lies what may be the purest threat to Microsoft's domination of the software industry.

Raymond, 40, is a full-time evangelist for "open-source" software, an idealistic concept once confined to the computing fringes, but one that has forged dramatic mainstream inroads in recent months. It dictates that software makers should grant access to their products' embedded "source code," or "digital DNA" -- the basic formula that makes them work. This would be somewhat akin to Coca-Cola Co. releasing its formula.

If adopted on a large scale, its proponents say, open-source would allow a vast body of technical talent -- nourished and connected by the Internet -- to tinker with and improve software's underlying recipe.

Software would become more reliable, Raymond tells audiences. Why? Because, in a closed company world, its creation is often not subject to independent peer review. This is why computers crash so often. Conversely, open-source provides a broad and rigorous universe of peers to root out problems.

In this collaborative environment, creativity would flourish. New business models would form. And Microsoft would be forced to assimilate or succumb.

At least that's the idea. It might seem utopian in a computing industry governed by intellectual property laws. But in recent years, successful companies have emerged that specialize in open-source products. Linux, an operating system attributed to Finnish engineer Linus Torvalds and enhanced through open-source collaboration, has become one of the fastest-growing software phenomena among fervent techies. Some major computing brands have adopted open-source formats. Microsoft is betraying fear of the movement in internal memos.

And Eric Raymond has evolved from a childhood pariah to a hacker cult figure to an unlikely industry player who is being consulted by some of Wall Street's biggest investors.

Last month, Raymond received a call from a Merrill Lynch & Co. vice president inviting him to preach open-source to a group of 70 institutional investors.

"With any luck, Microsoft's stock will drop the next day," he tells his Austin audience, which applauds. "I can dream, can't I?"

Raymond readily notes that Microsoft itself is not the "root of evil." Rather, it is "a symptom of closed-source disease."

Nonetheless, every revolution needs a villain. And in a psychological context, Microsoft -- and Gates -- represents a bully figure that has recurred as a theme of Raymond's life.

Raymond's only encounter with Gates took place in 1982. Raymond, then in his early twenties, was watching Microsoft's young CEO at a Philadelphia computing conference. He summoned the courage to ask a question.

Gates dismissed the question and turned it into a joke, Raymond recalls. The audience laughed, and Raymond slumped back into his seat, feeling small and shamed.

"I remember thinking, 'Damn you,' " Raymond says of the Gates exchange. "I said to myself, 'I'm going to become the kind of person that you can't casually blow off like that.' "

After his speeches, Raymond is often swamped by fans, some seeking autographs. They are usually male. (Of 250 who attended two Texas speeches last month, eight were women.) While mainly indifferent to Microsoft's antitrust battles, they are intent on toppling the software empire by different means.

Microsoft is fighting an entire mind-set it can't quash like it quashes companies, says Wesley Felter, a 20-year-old computer scientist, after the Austin speech. He wears a T-shirt bearing a quote by Linus Torvalds. "World Domination," the T-shirt says. "Fast."

As Raymond greets his followers, he is ecstatic. They are his intellectual, social and cosmic lifeline, his fellow "hackers," a term that demands some clarification. Contrary to popular terminology, a "hacker" does not commit digital mischief, explains Raymond, who edited the 1991 book "The New Hacker's Dictionary." "Those are 'crackers.' Hackers build things, crackers break them." Hackers are the most ardent of computer users, not content to master certain crafts but striving for full and near-spiritual immersion.

The history of the open-source movement is linked to entrenched hacker ethics. In the first days of the Internet, the 1960s, a spirit of cooperation pervaded computing. Consistent with Western scientific traditions -- and the academic and research settings where the Internet began -- the earliest hackers were encouraged to build on the creations of their peers.

But as computing has grown into a multitrillion-dollar industry, the ethic has been supplanted by proprietary rules and cutthroat competition. To many hackers, Microsoft is the embodiment of all that has soured in the computing realm -- both technically and socially.

After his UT speech, Raymond invokes the military theorist Sun Tzu to describe his strategy against Microsoft. "Supreme excellence in warfare is not winning battles. Supreme excellence in warfare is breaking the enemy's will without fighting," he says. "We have to drive Microsoft's PR apparatus crazy by convincing them that for everything they say and do, we will be all over them."

Recent example: In late October, Raymond received a leaked internal memo written by a Microsoft engineer named Vinod Valloppillil. The memo -- its authenticity confirmed by Microsoft -- concludes that open-source "pose[s] a direct, short-term revenue and platform threat to Microsoft." It assesses the potential destructive power of open-source software and suggests means by which Microsoft can combat this "threat." A second memo -- leaked to Raymond the next day -- focused on Linux.

Raymond dubbed these "The Halloween Documents" and promptly circulated them on the Internet.

Until recently, Microsoft has been mostly quiet on open-source. But at its antitrust trial, the company has mentioned Linux as a serious and emerging competitor. Cynics suggest that Microsoft is exaggerating these concerns -- and purposely leaking its memos -- to create the perception that it does not in fact have a software monopoly.

Microsoft officials deny this. "We recognize Linux as a serious competitor," says Ed Muth, a Microsoft group manager, who adds that the company is "working to understand the sociology of this so-called open-source movement."

"This is less about technology than other kinds of attitudes," he says. "Open source is a very different approach to software than ours. We feel that it is less likely to satisfy customers in the long term."

Such dismissiveness delights Raymond. It shows Microsoft is complacent. Likewise, it casts Raymond in an underdog role from which he derives inspiration. He sees his life as a procession of David-vs.-Goliath struggles, beginning in the schoolyard.

"I had a miserable childhood," says Raymond, who was born with cerebral palsy. "Being a short kid with a limp was not the easiest thing in the world. Children can be vicious." He retreated to the outcast existence of a computer nerd.

In addition to these social burdens, in his teenage years Raymond was saddled with the belief of some mentors that he was a math prodigy. "They might have been right, too, but I wasn't able to deal with it," Raymond says. He left the University of Pennsylvania after 2 1/2 years and never returned.

Today Raymond loves guns. He owns three, shoots at a range near his home and maintains "Eric's Gun Nut Page" on his home page. He is also a black belt in Tae Kwon Do. "I needed to become the kind of person for which the horrible memories of my childhood would not have crippling power," says Raymond. On political matters, he calls himself a "gonzo libertarian." This conforms to his computing ideology as well. "Open-source is a way to give power to individuals and deny coercive power to the government and monopolistic corporations," he says.

At the crux of Raymond's adult evolution has been his immersion in hacker life. It is a community of rules, customs, taboos and factions, and Raymond views himself a "tribal anthropologist" within it.

"Eric has a way of explaining what we're doing and why we're doing it," says Guido van Rossum, the inventor of a programming language called Python and a prominent figure among open-source proponents. Van Rossum, a gawky Dutchman who now lives in Reston, invited Raymond to address a group of Python software developers in Houston last month.

Until January of this year, Raymond had been proselytizing in the limited confines of the hacker community. But then came a seminal event in open-source history: Netscape Communications Corp. announced it would release the source-code for the next version of its popular browser software. "By giving away the source code . . . we can ignite the creative energies of the entire Net community," Netscape CEO Jim Barksdale said in a statement that day.

Netscape officials say their decision was guided in part by an essay Raymond wrote early in 1997. Titled "The Cathedral and the Bazaar," the essay is an oft-invoked manifesto in the open-source community. It posits that a free "bazaar" of hackers communing over the Internet can build better software than any closed "cathedral" such as Microsoft.

At the company's invitation, Raymond flew to Silicon Valley and consulted with Netscape -- on a volunteer basis -- to ease the transition to open source.

"Prior to that, I had been content to toil in hacker obscurity," Raymond says. But Netscape's decision was an unprecedented event -- a major commercial technology company adopting open-source.

"Finally, my people had gotten the breakthrough we've been waiting for." Now Raymond felt someone needed to devote full energy to "open-source evangelism." He felt suited.

"I'm one of those rare hackers that has the brain chemistry to be extroverted," says Raymond in an interview at his home in the Philadelphia suburb of Malvern, Pa. It also helps that his lawyer wife, Catherine, can help support him financially.

When not out preaching open-source, Raymond plots strategy from his home, a modest, mid-'60s ranch imbued with essence of ripe kitty litter. In his spare time, he operates a nonprofit Internet service provider that offers free Net access to underprivileged users in the Philadelphia area. He works on a large Linux-compatible workstation from VA Research, a Silicon Valley personal computer maker that specializes in Linux applications. It is worth $12,000, but was custom-made by VA Research free of charge because Raymond is a high-profile user (in the same way Nike gives Michael Jordan free sneakers).

Raymond fields several hundred e-mails a day from open-source disciples and corporate technical officers. Perhaps his most valuable asset is his skill at giving introverted technologists the rhetorical tools to explain themselves. "I'm trying to teach hackers a language to use to convey their model of the world to people who wear suits," he says.

"Reliability" is open-source's key selling point, he tells audiences. As proof, open-source believers say, Linux crashes far less often than proprietary operating systems. "Given enough eyeballs, all bugs are shallow," Raymond writes in "The Cathedral and the Bazaar."

Furthermore, Raymond tells audiences, open-source creates a dynamic "gift culture." Programmers create features and repair bugs in return for the prestige it brings them. It is akin, he says, to rich people making philanthropic donations.

Only the elite can participate -- the economic elite in philanthropy, the technical elite in software improvement -- but the broader community is still served in the end.

Of course this elitism represents a major roadblock as well: Open-source products such as Linux are generally far too complicated for average computer users. Raymond concedes this, but says as software improves through open-source teamwork, products will become more user-friendly.

"Does this mean we're all going to starve?" a UT student asks Raymond.

No, in an open-source universe, programmers will not end up flipping burgers, he assures the student.

Indeed, there is money to be made in open-source, says Raymond. Giving away source code does not preclude commercial viability. On the contrary, open-source greatly reduces a company's research, development and distribution costs.

Raymond calls himself a "happy capitalist," which puts him at odds with more utopian elements of the movement. He has clashed often with Richard Stallman, a legendary Boston hacker who prefers the term "free software" and believes Raymond's marketplace concerns miss the point.

"Where Eric focuses on merely practical goals," Stallman writes in an e-mail, "I'm concerned primarily about what kind of society we are going to live in."

"Free software is a matter of liberty, not price," he declares on his Web site.

Raymond says: "Most hackers don't have a problem with capitalism. But they do have a problem with closed-source resulting in bad engineering results."

Some open-source advocates have accused Raymond of promoting himself too aggressively. He has also been criticized for excessive deification of Torvalds ("Linus is God, I am the prophet," he says) and vilification of Microsoft.

Raymond denies that obliterating Microsoft is his goal. He is more ambitious than that. If Microsoft is destroyed in his revolution's path, "it's just a fringe benefit," he says.

Even so, open source remains a radical notion in many corporate realms. "Intellectual property laws have been around a long time," says Paul Everitt, CEO of Digital Creations, a Fredericksurg, Va., software company that has adopted open-source.

Last month he traveled to Houston to hear Raymond speak. "I'm trying to learn if the success of this movement is inevitable or if we're just tilting at windmills," he said. Everitt said Raymond's then-upcoming conference call with Merrill Lynch institutional investors could be "an inflection point" in open-source history.

The call took place Nov. 18. Raymond says it went very well -- enough so that he was invited to make a return appearance and to join Merrill Lynch's technology advisory board.